CN1084311C - Ceramic composition for absorbing electromagnetic wave and method for mfg. the same - Google Patents

Ceramic composition for absorbing electromagnetic wave and method for mfg. the same Download PDF

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CN1084311C
CN1084311C CN97102157A CN97102157A CN1084311C CN 1084311 C CN1084311 C CN 1084311C CN 97102157 A CN97102157 A CN 97102157A CN 97102157 A CN97102157 A CN 97102157A CN 1084311 C CN1084311 C CN 1084311C
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ceramic composition
molding
material powder
powder
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CN1176949A (en
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洪性镛
罗昌镐
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/26—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
    • C04B35/2658—Other ferrites containing manganese or zinc, e.g. Mn-Zn ferrites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
    • H01F1/36—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Power Engineering (AREA)
  • Dispersion Chemistry (AREA)
  • Magnetic Ceramics (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Soft Magnetic Materials (AREA)

Abstract

The present invention provides the ceramics composition material, which can absorb the electromagnetic waves generated from various kinds of electric and electronic equipments and the manufacturing method thereof. Powder raw material is constituted of 35-65wt.% of iron oxide, 1-5wt.% of aluminum oxide, 0.5-1.5wt.% of zinc, 0.5-1.0wt.% of chromium. 3-10wt.% of copper, 3-8wt..% of manganese and 1-4wt.% of cobalt. For the powder raw material, 30-45wt..% of water, 1.5-2.0wt.% of dispersing agent and 1.5-2.0wt.% of plasticizere are compounded. Also publiced the way to producing attenuation ceramics using this composition.

Description

Absorb electromagnetic ceramic composition and manufacture method thereof
The present invention relates to a kind of ceramic composition and with its method of making pottery, particularly relate to a kind of ceramic composition and can absorb by method as electromagnetic potteries that electrical means produced such as cellular phone, pager, computer, cordless telephones in order to make.
Normally, fine ceramics or novel new ceramics they composition and their shaping and production methods such as sintering aspect with traditional ceramic different, promptly, fine ceramics is by a kind of like this manufacturing process and a kind of sintering method and produce, promptly by adopting a kind of artificial material powder or a kind of highly purified material powder accurately to control furnish component.So fine ceramics has more purposes than conventional ceramic.Owing to found the multiple use of fine ceramics recently, so fine ceramics is used to realize multiple purpose.
Fine ceramics generally is classified as oxide type pottery and non-oxide ceramic.The oxide type pottery comprises aluminum oxide (Al 2O 3), ferrite (Fe 2O 3), zirconium dioxide (ZrO 2) and titanium dioxide (TiO 2) etc.Non-oxide ceramic comprises silicon carbide (SiC) and silicon nitride (Si 3N 4) etc.At present, the new application of fine ceramics, among for example hot application, machine applications, biological chemistry application, electrical applications, electronic application and optical application etc. are being excavated, and the research of these application of relevant fine ceramics will continue.
At present, many electric and electronic devices are applied in daily life as cellular phone, pager, computer, cordless telephone and televisor etc.In modern life, it is very necessary utilizing these electronicss, but most these electrical meanss launching electromagnetic wave all.As everyone knows, the hertzian wave that emits of these electrical meanss is deleterious to the people who uses these electric and electronic devices.Therefore, the relevant electromagnetic research association that is emitted by these electrical meanss that shields proceeds down.A kind of section (pellet) that is used to make electromagnetic shielding material is disclosed for the 4th, 960, No. 642 at the United States Patent (USP) of authorizing Izumi Kosuga etc.By electro-conductive fiber being inserted in the matrix resin, this section can be with electromagnetic wave shielding.In addition, people have also proposed a kind of by a ferrite core is contained in these electrical meanss, in order to absorb the electromagnetic method that is emitted by electrical means.
But, above-mentioned section and ferrite core screen method all can not shield the hertzian wave of being launched by these electrical meanss fully, and because the section and magnetic core be inserted on the circuit card of calutron, so that the structure of the manufacturing method and apparatus of these devices is all very complicated.
Consider the problems referred to above, first purpose of the present invention just provides a kind of ceramic composition, by this ceramic composition being installed on the predetermined position of electrical means, in order to absorb the hertzian wave that electrical means is launched.
Second purpose of the present invention provides the method that a kind of manufacturing is used to absorb electromagnetic pottery, and this method is particularly suitable for making this pottery.
To achieve the above object, be used to absorb electromagnetic ceramic composition and comprise according to of the present invention:
Calculate by weight the Fe between about 40% to about 50% 2O 3, the Al between about 1% to about 5% 2O 3, the Co between the Mn and about 1% to about 4% between the Cu, about 3% to about 8% between the Cr, about 3% to about 10% between the Zn, about 0.5% to about 1% between about 0.5% to about 1.5%;
Softening agent between the dispersion agent between the water between about 30% to about 45%, about 1.5% to about 2.0% and about 1.5% to about 2.0%.
Preferably, material powder comprises about by weight 45% Fe 2O 3
Comprise about by weight 40% to about 50% Fe when material powder 2O 3The time, its to the specific absorption in electric field that electrical means produced and magnetic field between 36.6% to 54.3%.Especially comprise about by weight 45%Fe at material powder 2O 3Situation under, when with Holaday HI 4000 type radio frequency test systems test specific absorption, the specific absorption of electric field be maximum, its value is 41.2%, and the specific absorption in magnetic field is maximum, its value is 52.8%.When comprising, material powder is lower than 35% Fe by weight 2O 3The time, because the compact density of material powder reduces, make its specific absorption become and be lower than about 30% electric field and magnetic field.In addition, comprise about 65% Fe by weight when material powder 2O 3The time, may difficulty owing to grind material powder and adjust the particle size of material powder, so during the raw materials for sintering powder, the particulate size of material powder can be grown excessively, make the specific absorption in electric field and magnetic field become and be lower than 30%.
Dispersion agent comprises at least from by pregnancy alcohol (hexamethanol), polyvinyl alcohol (polyvinylalcohol), and a kind of material of selecting in the group formed of polyethylene (polyethylen).
In addition, softening agent comprises at least a from by gelatin (gelatin), the material of picking out in the group that dextrin (dextrin) and Mierocrystalline cellulose (cellulose) are constituted.
In addition, to achieve the above object, according to the present invention, be used to make the method that absorbs electromagnetic pottery, the step that comprises has:
I) mixture of a material powder with a material powder mixed equably, wherein this material powder comprises the Fe between about by weight 40% to about 50% 2O 3, the Al between about 1% to about 5% 2O 3, the Co between the Mn and about 1% to about 4% between the Cu, about 3% to about 8% between the Cr, about 3% to about 10% between the Zn, about 0.5% to about 1.0% between about 0.5% to about 1.5%; And this mixture comprises the softening agent between the dispersion agent and about 1.5% to about 2.0% between the water, about 1.5% to about 2.0% between about by weight 30% to about 45%;
Ii) grind through the blended powder;
Iii) the powder granulation through grinding is formed granulated pellet;
Iv) granulated pellet is formed a molding;
This molding of v) this molding of roasting, and sintering is to form a sintered compact;
Vi) with this sintered compact cools down.
Step I i) be a kind of wet lapping method, this method was used a ball mill grinding 45 hours to 50 hours, made to have size-grade distribution between about 1 micron to about 3 microns through the blended powder.Step I ii) is a kind of spray-drying process.
Preferably step I v) is by utilizing a pressure at 800kg/cm 2With 1200kg/cm 2Between the stamped metal device granulated pellet is shaped, thereby form a cylindrical molding with a through hole.When forming cylindrical molding, be lower than 800kg/cm at pressure 2Condition under, can not be formed into body; At pressure greater than 1200kg/cm 2Condition under, granulated pellet is by undue compacting, so in the process of sintered shaped body, the crystal grain of granulated pellet is grown up excessively.
Preferably, step is roasting molding ten hours to 12 hours in the stove of inflated with nitrogen atmosphere v), the body 1.5 hours to 2.5 hours of baking with agglomeration in temperature is stove between 1300 ℃ to 1500 ℃ then.When sintering time between 1.5 hours to 2.5 hours, and sintering temperature is 1400 ℃, the sintered compact that can obtain having optimum shape and grain-size.
Therefore, according to pottery of the present invention,, just can absorb the hertzian wave that these electrical meanss emit by it is installed on the preset position of electrical meanss such as cellular phone, pager, computer, cordless telephone, TV.
Above-mentioned purpose of the present invention and some other advantage will more clearly display by detailed description of the preferred embodiment.
Embodiment 1
With a kind of Fe of about by weight 60% that comprises 2O 3, about 5% Al 2O 3, about 1%Zn, about 8% Cu, about 3% Mn and about 2% Co material powder and a kind of material powder mixture that comprises the gelatin as softening agent (gelation) of about by weight 40% water, about 1.5% the dispersion agent that constitutes by pregnancy alcohol (hexamethanol) and polyvinyl alcohol (polyvinylalcohol) and about 2.0% mix equably.Fe 2O 3Be a kind of powder of producing by Kyocera Co., Al 2O 3Be a kind of powder of being produced by Sumitomo Co., pregnancy alcohol, polyvinyl alcohol and gelatin are produced by Sannop Co..
Next, utilize the wet lapping method, in a ball mill, will grind 45 hours to 50 hours through the blended powder, preferably 48 hours, so that particle size dispersion is between 1 micron to 3 microns.Then, utilize spray-drying process,, the powder granulation is formed the particle of granulation through a dressing sieve with 120 order/inches.
Utilize a stamped metal device to be 1000kg/cm in room temperature and pressure 2Condition press down the particle of making grain, have the columniform molding of a reach through hole with formation.In this case, the density of molding is 2.8g/cm 3Next, molding roasting 12 hours in the stove of inflated with nitrogen, sintering is 2 hours in 1400 ℃ stove.Then, so just made the pottery that cylindrical molding is arranged with the stove cools down.
The electric field that the cellular phone that lg electronics company is produced produces and the specific absorption in magnetic field are shown in Table 1.The electric field of the generation shown in the table 1 and magnetic field and specific absorption are to utilize Holaday HI-400 type radio-frequency measurement system, measure at the interval of 5 centimetres of distance cellular phones.
Table 1
Pottery is not installed ceramic specific absorption (%) is installed
Electric field (V/m) 29.2 18.5 36.6
Magnetic field (mG) 4.69 2.74 41.6
Referring to table 1, after pottery was installed on the cellular phone, electric field was 18.5V/m, and magnetic field is 2.74mG.When pottery not being installed on the cellular phone, electric field is 29.2V/m, and magnetic field is 4.69mG.Therefore ceramic composition is respectively 36.6% and 41.6% to the specific absorption in electric field and magnetic field.
Table 2 has shown the specific absorption of the electric field of the cellular phone generation that Samsung Electronics is produced.Electric field shown in the table 2 and specific absorption are that the 8700 type measuring systems of utilizing U.S. Narda to produce record at the interval of 2 centimetres of distance cellular phones.
Table 2
Pottery is not installed ceramic specific absorption (%) is installed
Electric field (V/m) 22.4 11.1 50.4
Referring to table 2, on cellular phone, to have installed after the pottery, electric field is 11.1V/m.When pottery not being installed on the cellular phone, electric field is 29.2V/m.Therefore, pottery is 50.4% to the specific absorption of electric field.
Therefore, as shown in Table 1 and Table 2, most of electric field and the magnetic field that electrical means produces can be sponged according to embodiment 1 resulting pottery.
As mentioned above, pottery of the present invention can absorb most electric field and the magnetic field that electrical means produces.That is, this pottery can absorb the hertzian wave that electrical means produces.
Embodiment 2
With a kind of Fe of about by weight 50% that comprises 2O 3, about 3% Al 2O 3, about 1%Zn, about 5% Cu, about 5% Mn and about 2% Co material powder and a kind of material powder mixture that comprises the gelatin as softening agent (gelatin) of about by weight 40% water, about 1.5% the dispersion agent that constitutes by pregnancy alcohol (hexamethanol) and polyvinyl alcohol (polyvinylalcohol) and about 2.0% mix equably.
Next, utilize the wet lapping method, in a ball mill, will grind 45 hours to 50 hours through the blended powder, preferably 48 hours, so that particle size dispersion is between 1 micron to 3 microns.Then, utilize spray-drying process,, the powder granulation is formed the particle of granulation through a dressing sieve with 120 order/inches.
Utilize a stamped metal device to be 1000kg/cm in room temperature and pressure 2Condition press down the particle of making grain, have the columniform molding of a reach through hole with formation.In this case, the density of molding is 2.8g/cm 3Next, molding roasting 12 hours in the stove of inflated with nitrogen, sintering is 2 hours in 1400 ℃ stove.Then, so just made the pottery that cylindrical molding is arranged with the stove cools down.
The electric field that the cellular phone that lg electronics company is produced produces and the specific absorption in magnetic field are shown in Table 3.The electric field of the generation shown in the table 3 and magnetic field and specific absorption are to utilize Holaday HI-400 type radio-frequency measurement system, measure at the interval of 5 centimetres of distance cellular phones.
Table 3
Pottery is not installed ceramic specific absorption (%) is installed
Electric field (V/m) 28.3 17.5 38.2
Magnetic field (mG) 4.72 2.76 41.5
Referring to table 3, after pottery was installed on the cellular phone, electric field was 17.5V/m, and magnetic field is 2.76mG.When pottery not being installed on the cellular phone, electric field is 28.3V/m, and magnetic field is 4.72mG.Therefore ceramic composition is respectively 38.2% and 41.5% to the specific absorption in electric field and magnetic field.
Table 4 has shown the specific absorption of the electric field of the cellular phone generation that Samsung Electronics is produced.Electric field shown in the table 2 and specific absorption are that the 8700 type measuring systems of utilizing U.S. Narda to produce record at the interval of 2 centimetres of distance cellular phones.
Table 4
Pottery is not installed ceramic specific absorption (%) is installed
Electric field (V/m) 24.7 11.3 54.3
Referring to table 4, after on the cellular phone pottery being installed, electric field is 11.3V/m.When pottery not being installed on the cellular phone, electric field is 24.7V/m.Therefore pottery is 54.3% to the specific absorption of electric field.
Therefore, shown in table 3 and table 4, most of electric field and the magnetic field that electrical means produces can be sponged according to embodiment 2 resulting potteries.
Embodiment 3
With a kind of Fe of about by weight 45% that comprises 2O 3, about 3% Al 2O 3, about 0.5%Zn, about 3% Cu, about 8% Mn and about 3% Co material powder and a kind of material powder mixture that comprises the gelatin as softening agent (gelatin) of about by weight 40% water, about 1.5% the dispersion agent that constitutes by pregnancy alcohol (hexamethanol) and polyvinyl alcohol (polyvinylalcohol) and about 2.0% mix equably.
Next, utilize the wet lapping method, in a ball mill, will grind 45 hours to 50 hours through the blended powder, preferably 48 hours, so that particle size dispersion is between 1 micron to 3 microns.Then, utilize spray-drying process,, the powder granulation is formed the particle of granulation through a dressing sieve with 120 order/inches.
Utilize a stamped metal device to be 1000kg/cm in room temperature and pressure 2Condition press down the particle of making grain, have the columniform molding of a reach through hole with formation.In this case, the density of molding is 2.8g/cm 3Next, molding roasting 12 hours in the stove of inflated with nitrogen, sintering is 2 hours in 1400 ℃ stove.Then, so just made the pottery that cylindrical molding is arranged with the stove cools down.
The electric field that the cellular phone that lg electronics company is produced produces and the specific absorption in magnetic field are shown in Table 5.The electric field of the generation shown in the table 5 and magnetic field and specific absorption are to utilize Holaday HI-400 type radio-frequency measurement system, measure at the interval of 5 centimetres of distance cellular phones.
Table 5
Pottery is not installed ceramic specific absorption (%) is installed
Electric field (V/m) 28.4 16.7 41.2
Magnetic field (mG) 4.75 2.24 52.8
Referring to table 5, after pottery was installed on the cellular phone, electric field was 16.7V/m, and magnetic field is 2.24mG.When pottery not being installed on the cellular phone, electric field is 28.4V/m, and magnetic field is 4.75mG.Therefore ceramic composition is respectively 41.2% and 52.8% to the specific absorption in electric field and magnetic field.
Table 6 has shown the specific absorption of the electric field of the cellular phone generation that Samsung Electronics is produced.Electric field shown in the table 6 and specific absorption are that the 8700 type measuring systems of utilizing U.S. Narda to produce record at the interval of 2 centimetres of distance cellular phones.
Table 6
Pottery is not installed ceramic specific absorption (%) is installed
Electric field (V/m) 22.4 8.4 62.5
Referring to table 6, on cellular phone, to have installed after the pottery, electric field is 8.4V/m.When pottery not being installed on the cellular phone, electric field is 22.4V/m.Therefore pottery is 62.5% to the specific absorption of electric field.
Therefore, shown in table 5 and table 6, most of electric field and the magnetic field that electrical means produces can be sponged according to embodiment 3 resulting potteries.
As mentioned above, pottery of the present invention can absorb most electric field and the magnetic field that electrical means produces.That is, this pottery can absorb the hertzian wave that electrical means produces.
Although with reference to some specific embodiments the present invention has been carried out detail display and description, those skilled in the art still can do multiple remodeling and change under the situation that does not exceed the essence that limited by appended claim and scope.

Claims (13)

1, a kind ofly be used to absorb electromagnetic ceramic composition, calculate by weight and comprise:
Fe between 40% to 50% 2O 3,
Al between 1% to 5% 2O 3,
Zn between 0.5% to 1.5%,
Cr between 0.5% to 1%,
Cu between 3% to 10%,
Mn between 3% to 8%,
Co between 1% to 4%,
Water between 30% to 45%,
Dispersion agent between 1.5% to 2.0% and
Softening agent between 1.5% to 2.0%,
Wherein, Fe 2O 3, Al 2O 3, Zn, Cr, Cu, Mn, Co constitute material powder, and water, dispersion agent and softening agent constitute the mixture of material powder.
2, according to claim 1ly be used to absorb electromagnetic ceramic composition, wherein, above-mentioned material powder comprises 45% Fe by weight 2O 3
3, according to claim 1ly be used to absorb electromagnetic ceramic composition, wherein, above-mentioned dispersion agent comprises at least a material of selecting from the group of being made up of pregnancy alcohol, polyvinyl alcohol and polyethylene.
4, according to claim 1ly be used to absorb electromagnetic ceramic composition, wherein, above-mentioned softening agent comprises a kind of material of picking out at least from the group of being made up of gelatin, dextrin and Mierocrystalline cellulose.
5, with described ceramic composition one of among the claim 1-4 as absorbing electromagnetic material.
6, a kind of manufacturing is used to absorb the method for electromagnetic pottery, and the step that this method comprises has:
I) will have that following weight forms one by Fe 2O 3, Al 2O 3, the material powder that constitutes by water, dispersion agent and softening agent of the material powder that constitutes of Zn, Cr, Cu, Mn, Co and mixture mix equably:
Fe between 40% to 50% 2O 3,
Al between 1% to 5% 2O 3,
Zn between 0.5% to 1.5%,
Cr between 0.5% to 1%,
Cu between 3% to 10%,
Mn between 3% to 8%,
Co between 1% to 4%,
Water between 30% to 45%,
Dispersion agent between 1.5% to 2.0% and
Softening agent between 1.5% to 2.0%,
Ii) grind through the blended powder;
Iii) the powder granulation through grinding is formed granulated pellet;
Iv) granulated pellet is formed a molding;
This molding of v) this molding of roasting, and sintering is to form a sintered compact;
Vi) with this sintered compact cools down.
7, be a kind of wet lapping method method according to claim 6, wherein, described step I i), this method was used a ball mill grinding 45 hours to 50 hours, made to have size-grade distribution between about 1 micron to about 3 microns through the blended powder.
8, method according to claim 6, wherein, described step I ii) is a kind of spray-drying process.
9, method according to claim 6, wherein, described step I v) is by utilizing a pressure at 800kg/cm 2With 1200kg/cm 2Between the stamped metal device granulated pellet is shaped, thereby form a cylindrical molding with a through hole.
10, method according to claim 6, wherein, described step is roasting molding 10 hours to 12 hours in the stove of inflated with nitrogen atmosphere v), the body 1.5 hours to 2.5 hours of baking with agglomeration in temperature is stove between 1300 ℃ to 1500 ℃ then.
11, according to the described method of one of claim 6-10, wherein, above-mentioned material powder comprises 45% Fe by weight 2O 3
12, according to the described method of one of claim 6-10, wherein, above-mentioned dispersion agent comprises at least a material of selecting from the group of being made up of pregnancy alcohol, polyvinyl alcohol and polyethylene.
13, according to the described method of one of claim 6-10, wherein, above-mentioned softening agent comprises a kind of material of picking out at least from the group of being made up of gelatin, dextrin and Mierocrystalline cellulose.
CN97102157A 1996-09-19 1997-01-28 Ceramic composition for absorbing electromagnetic wave and method for mfg. the same Expired - Fee Related CN1084311C (en)

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EP0831074A2 (en) 1998-03-25
IL120061A (en) 2000-07-16
JP2795406B2 (en) 1998-09-10
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EP0831074B1 (en) 2001-06-27
JPH10116718A (en) 1998-05-06
KR19980021940A (en) 1998-06-25
DE69705372T2 (en) 2002-05-16
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EP0831074A3 (en) 1998-10-07
DE69705372D1 (en) 2001-08-02
IL120061A0 (en) 1997-04-15

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